Inflatable underwater platform

ABSTRACT

An inflatable support platform which may be dropped into the water while compactly folded. Upon reaching a predetermined depth, the device is erected by pumping ambient water by a selfcontained pump into the inflatable, flexible, soft-walled water impermeable structure. The inflated structure may consist of several inflated tubular arms connected together in various geometric shapes or may be a single flat enclosed body. The inflated structure is stable in both orientation and depth.

United States Patent 1 Mar et al.

[ Apr. 9, 1974 INFLATABLE UNDERWATER PLATFORM [75] Inventors: John Mar, Ottawa, Ontario; Todd Garrett, Kanata, Ontario; Albert H. Reynaud; Frank Vigneron, both of Ottawa, Ontario, all of Canada; Robert J. Gerrish, Kirkland, Wash.

[73] Assignee: Her Majesty the Queen in right of Canada as represented by the Minister of National Defence 22 Filed: Nov. 7, 1968 211 Appl. No.: 775,993

[52] U.S. Cl. 340/2, 9/8 R, 73/170 A, 340/8 S [51] Int. Cl. G01s 3/80, B63b 21/00 {58] Field of Search 340/2, 8 R, 8 S, 9; 9/8 R; 73/170 A [56] References Cited UNITED STATES PATENTS 3132.322 5/l964 Maes 340/2 3.44451 1 5/ l 969 Morrow 340/9 Primary Examiner-Richard A. Farley Attorney, Agent, or FirmR. I. Tompkins; Arthur L. Branning; R. J. Erickson [5 7 ABSTRACT An inflatable support platform which may be dropped into the water while compactly folded. Upon reaching a predetermined depth, the device is erected by pumping ambient water by a self-contained pump into the inflatable, flexible, soft-walled water impermeable structure. The inflated structure may consist of several inflated tubular arms connected together in various geometric shapes or may be a single flat enclosed body. The inflated structure is stable in both orientation and depth.

1 Claim, 15 Drawing Figures PATENTEDAPR 919M $803540 SHEEI 1 UF 5 INVENTORS JOHN MAR TODD GARRETT ALBERT H. RE Y/VAUD ROBERT J. GERR/SH FRANK WGNERON MM ATTORNEYS QATENTEBAPR 91914 3.803; 540

sum 2 or e I N VEN TORS JOH 1v MAR r000 GARRETT ALBERT H. REY/VAUD ROBERT .1. cam/s BY ma/wr VIGNERON I ATTORNEYS ATENTED APR 9 I974 SHiU 3 OF 6 FIG. 7

INVENTORS JOHN MAR T000 GARRETT ALBERT H. REYNAUD GERR/SH V/GWERON ROBERT J. BY FRANK ATTORNEYS ATENTED R 9 I974 FIG. 8

INVENTORS JOHN MAR TODD GARRETT ALBERT H. RE YNAUD 0BERT J.

GERR/SH %VK V/GNERON ATTORNEYS JATENTEDAPR 91974 3,803,540

sum 5 0F 6 INVENTORS JOHN MAR TODD GARRETT ALBERT H. RE YNAUD ROBERT J. GERRISl-I FRANK VI GIVE RON 402M ATTORNEYS "ATENTEUAPR 9:914

SHEET 6 BF 6 FIG. /0

INVENTORS MAR GARRETT H. RE YNAUD GERRISH V/GWE RON ATTORNEYS INFLATABLE UNDERWATER PLATFORM The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to expandable elements and more particularly to a device which is inflatable by water.

In many maritime fields, e.g., oceanography, fisheries, marine prospecting, etc., there is a requirement for an element which may act as a supporting or stabilizing platform or indeed a marker or like platform, which is inherently stable in orientation and depth after it has been erected, and which is easily transportable in the collapsed state.

The general purpose of the present invention is to provide a new and improved underwater platform. In accordance with the present invention, a new article of manufacture is provided having a water inflatable, flexible, soft-walled, water impermeable element and means for connecting the element to means for supplying water thereto to cause said element to form a semirigid structure of predetermined configuration.

Since the collapsed element, hereinafter referred to as the package," inflates when water is forced into it, it is possible to discharge a relatively small package from craft which heretofor could not physically accommodate a sizable, rigid, non-collapsible structure. The packaged article of this invention is even capable of being dropped from aircraft, the inflation of the package only taking place after the package has hit the water and sunk to a desired depth.

According to a feature of the invention, the means for connecting the element to means for supplying water includes water pump means operatively connected to the element for pumping inflating ambient water into the element to erect it. This pump means, according to a preferred embodiment, may comprise a self-contained pump mounted on the package and operable by a suitable switch to inflate the element at a prescribed depth, preferably beneath the water surface, to thereby minimize surface effects. The package, in the collapsed condition, because of low hydrostatic drag, sinks rapidly to the desired depth. By pumping ambient water at that depth to inflate the structure, the effects of hydrostatic head can be ignored since the pressure inside the inflated element approximates to the pressure of the surrounding water.

The element may be constructed from a material having a specific gravity greater or less than one, thus selectively imparting to the inflated structure a negative or positive buoyancy. The inflated structure may be towed, floated, suspended from a surface float, or anchored on the sea bottom. The material used in constructing the element, which is to take a predetermined configuration once inflated, is preferrably a pliant substance having the desired specific gravity and which has a tensile strength capable of withstanding internal water pressures in excess of 2 psi of the ambient water pressure.

The structural configuration of the inflated element is dictated by the purpose to which the structure is to be put. For example, as a supporting platform for hydrophones and the like, the erected structure may comprise only a single elongated arm or tube, or a plurality of interconnected arms or tubes. Where the inflated element consists of more than one arm, the structure may take, for example, a delta or star shape. Further, the inflated element may be toroidal, or it may be a unitary body of suitable peripheral configuration such as, for example, a disc or a triangle.

It is a feature of the invention to arrange sensing means on the collapsed element or package in a predetermined pattern, so that their relative positions and spacings one from the other are known when the element is ultimately inflated.

As an additional feature of this invention, the package may be housed within a cannister which acts as a protective casing for the relatively delicate collapsed element and sensing means. The cannister and package may be introduced into the water as a unit, separation of the two only taking place after they are in the water. Preferably, the cannister is positively buoyant and contains telemetry means for transmitting the information received by the sensing means on the inflated structure. A tether, carrying a communication link between the telemetry means of the cannister and the sensing means of the inflated element, is the only physical connection between the otherwise separated, water deployed, cannister and element.

An object of this invention is to provide a new and improved underwater platform.

Another object of the invention is to provide an underwater platform which will remain stabile in both depth and orientation after the platform has been placed in position.

A further object of the invention is to provide the underwater platform which makes into a compact unit for portability and which is self-erecting when placed in position.

The following is a description by way of example of certain embodiments of the invention; reference being had to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a submerged, inflated star" structure, tethered to a surface communication float or cannister;

FIG. 2 is a sectional view of a collapsed star structure housed in a cannister;

FIG. 3 is a plan view of a different collapsed form of a star structure;

FIG. 4 is a plan view of the star structure of FIG. 3 when in its inflated condition;

FIG. 5 is a plan view of a delta structure in its collapsed condition;

FIG. 6 is a plan view of the structure shown in FIG. 5 when in its inflated state;

FIG. 7 is a schematic illustration of another form of structure;

FIGS. 8 and 9 is a pictorial representation and side view, respectively, of an inflated disc-shaped structure;

FIG. 10 is a plan view of a toroidal structure;

FIG. 11 is a schematic illustration of a semi-toroidal structure supporting a fishnet;

FIG. 12 is a plan view of a semi-rigid structure which may be towed behind a water craft;

FIG. 13 is a sectional view of a communication buoy showing a collapsed stabilizing element contained in it;

FIG. 14 is the buoy of FIG. 13 shown with the stabilizing element extended; and

FIG. 15 is a perspective view of a coiled element having an adhesive strip formed thereon.

Referring now to the drawings and particularly to FIGS. 1 through 4, a water inflated flexible soft-walled structure of star" configuration is shown inflated in FIGS. 1 and 4 and in different forms of collapsed configuration in FIGS. 2 and 3. The structure has three arms 1, 2 and 3 of water impermeable material uniformly radiating in star form from a center header member 4. The center header member contains means for supplying water to the element which means comprises a pump communicating with the surrounding water and with the inside of each of the three arms through a one-way valve arrangement and driven by a water immersible battery. The battery may be actuated by condition sensitive means, for example, a hydrostatic switch, a time delay switch (such as a soluble plug) or a signal responsive switch. The arms provide a platform for any suitable form of sensing means, and in the drawings carry hydrophones 5, 6 and 7 mounted on the arms adjacent their ends. As illustrated in FIG. 1, the header is connected by means of a tether 12 through a compliant element 13 with a positively buoyant cannister 8. The cannister 8 carries an antenna 9, telemetry equipment 10, and battery 11; the tether 12 providing a communication means for the hydrophones 5, 6 and 7 so that the information obtained therefrom may be relayed for transmission by telemetry equipment 10.

As seen in FIG. 2, the structure may be collapsed to form a package so that the arms in the deflated condition are coiled about their respective hydrophones and stacked together with the header and tether inside the cannister.

In operation, when the cannister is dropped into the water, some suitable means is used to permit the negatively buoyant package portion consisting of arms 1, 2 and 3 and header 4 to separate from the cannister. For example, a mechanically released impact plate may be located at the bottom end of the cannister, which releases on hitting the water to permit the package portion to sink from the now open end of the cannister on the tether 12. When the package reaches a predetermined depth, the water pump is actuated by the hydrostatic switch, or other suitable switching means, to cause it to pump ambient water into the arms to erect the structure.

Because the arms and header are slightly negatively buoyant, the expanded structure tends to be suspended at the required depth on the end of the tether 12, but since the structure has been inflated by ambient water and since it is beneath the surface of the sea, the inflated structure generally maintains both its horizontal planar position and orientation and is not, to any appreciable degree, altered from its original inflated position. This is because the inflating media provides a large inertial mass for the structure, and this, without the penalty of additional weight. Furthermore, since the structure is inflated by ambient water, any tilting action of the structure produces a change in buoyancy between the lower and upper parts of the structure due to the slight compressibility of water, resulting in a tendancy to return the structure to its horizontal position. The hydrophones now are set in a predetermined pattern and information from the hydrophones is transmitted through a communication link carried by the arms and tether 12 to the telemetry equipment 10, and thence to a remote receiving station. The communication link carried by the arms is preferably located internally of the arms, but may, if desired, be carried exteriorly or even embedded in the walls of the arms.

In the construction of FIGS. 3 and 4, the arms 1, 2 and 3, instead of being coiled and stacked in the cannister as shown in FIG. 2, may be coiled about the hydrophones in a configuration which radiates from the header 4 as best seen in FIG. 3.

It will be obvious that any suitable configuration other than a star configuration may be adopted for this particular use of the invention, and indeed, the arms may be interconnected in a delta configuration as shown in FIG. 6.

The element of the delta structure of FIG. 6, seen in its collapsed state in FIG. 5, comprises arms 21, 22 and 23 which are interconnected at their ends by headers 24, 25, 26 to form a delta configuration. Each of the arms in the collapsed state is centrally coiled to form coiled sections 27, 28 and 29. When the arms are pumped with water, as before, they uncoil to form the fully inflated and erected delta configuration illustrated. In this configuration each header 24, 25 and 26 is self-contained and contains its own battery operated pump, operating as before, to inflate one arm of the element. Alternatively, one header may house the pumping arrangement, the remaining headers acting only as water conduit connecting links between the arms of the element.

With certain materials, expansion of the arms 1, 2, 3, 21, 22 and 23 from their collapsed coiled state may encounter difficulty due to buckling caused by premature uncoiling or unravelling. In order to ensure uniform sequential uncoiling, it is under these circumstances desirable to provide some form of expansion control element, such as a constant zipper comprising strips 81 and 82 arranged longitudinally of and secured to arm in the manner shown in FIG. 15. Thus, when the collapsed arm is coiled, an adhesive interface is effectively formed between adjacent loops of the coil. The contact zipper may suitably take the form of double sided masking tape. Moreover, while tight coiling of each of the arms helps reduce the amount of entrapped air, there will nevertheless be a certain amount of residual air contained in each of the coiled arms. In order to remove this unwanted air, the header is connected to the arms 1, 2, 3, 21, 22 and 23, so that, when expanded, the arms adopt a slightly acclivous attitude in the water with the consequence that entrapped residual air flows up to the header member and is expelled therefrom through an air release valve.

It is desirable under some operating conditions, for example, where it is desired to deploy the platform in areas where very strong current is prevalent, or perhaps to tow the structure through water, to choose a structure which, instead of being formed from arms I, 2, 3 or 21, 22, 23, may be of one piece streamlined configuration such as the disc 50 of FIGS. 8 and 9 or the triangular configuration 40 shown in FIG. 7. Element 51 of disc 50 is provided with a central header 52 located on the top portion thereof. Constricting gussets 53, 54, 55, 56, 57 and 58 are arranged in a radial fashion inside element 51 and are secured to the top and bottom walls of the element 51. The gussets serve to prevent the element from ballooning when water is pumped into it at a pressure in excess of the ambient water pressure. Preferably, gussets 53, 54, 55, 56, 57 and 58 as well as gussets 42, 43 and 44 of element 41, are made from the same flexible material used in the construction of the element and are arranged so as to permit free distribution of pumped ambient water inside the element. Header members 52 and 45 may conveniently be located as shown. Header 45 may additionally serve as a water pressure source for water inflatable stabilizing fins 46, 47 and 48, as well as acting as a securing point for tether 49.

As in all the previous configurations described, bydrophones may be arranged on the inflated streamlined configurations at preselected positions. Indeed, tether 49 may, as before, act as a communication link between the hydrophones and a surface communication buoy containing telemetry equipment, or it may function solely as a tow cable, recording equipment for the information received at the hydrophones being provided in header 42, the recorder of course being recoverable.

Yet a further configuration for the structure, that of a toroid, is shown in FIG. 10. Here, the three arms of FIGS. 1 through 6 are replaced by a substantially annular tube 30, interrupted only at a point to provide a header which may house a self-contained pump means functioning in the manner previously described. The tube may be connected at both ends to the header, or may be, as shown, connected only at one end to the header.

In FIG. 11 there is shown a construction similar to that of FIG. but of semi-toroidal configuration rather than the full toroid. This configuration may be used to support a fishnet 36. To initially set the net 36, the net is secured along the full length of the collapsed element 35. Water is then pumped into the element through header or connecting means 37. As the element takes its semi-toroidal shape, it carries with it net 36 until it takes the set position shown in FIG. 11. A valve in header 37 is then closed in order to maintain the positive pressure in the element 36 which is necessary to keep it semi-rigid. Net 36 and the element 35 and any entrapped fish are recovered by pursing the net 36 and opening the valve in header 37 to release the internal water pressure of element 35.

A further form of ship towable semi-rigid inflated structure is shown in FIG. 12. Here, tow cable 60 may carry a water hose connected to a water pump on board ship and to the header 61 of the element, the structure consisting of arms 62 and 63 which, if desired, may be formed of aerofoil cross section. The ship borne pump preferably draws water for pumping from the same level at which the structure is to be towed, so that the pumped water is ambient.

At selected locations along the trailing edge of arms 62 and 63 are provided water discharge orifices 64. Water under pressure is continuously supplied to the structure so as to maintain it in its semi-rigid state, yet permitting sufficient quantities of pressurized water to be discharged through orifices 64 to assist in the propulsion of the structure. Bleed-off ports 65 control the boundry layer around the structure for drag reduction purposes.

A third arm, 66, shown in phantom, may also be provided and be positioned between the trailing ends of arms 62 and 63 and connected thereto by water conduit headers 67 and 68. Arm 66, which completes the delta configuration, also includes water discharge orifices 69 and ports 69, ports 69' functioning in a manner similar to the ports 65.

FIGS. 13 and 14 show a further use to which the present invention may be put, that of a stabilizer. A buoy 70, to be stabilized, carries telemetry means 71, battery 72 therefor, and antenna 73. A water pump 74, inflatable element 75, tether 76, and hydrophone 77, are packed within the buoy prior to use and retained therein by a mechanically released impact plate 78.

Once the buoy strikes the water the plate is released and water reaches the salt water battery 79 which actuates the pump 74. This pumps ambient water into the collapsed element 75 and forces it downwardly through the bottom of the buoy 70. The pump continues to pump ambient water as it leads the now inflating element 75 and forms a stabilizing member. Hydrophone 77 is suspended by tether 76 from the lower portion of extended element 75 and is electrically connected with the telemetry means 71. Since inflated and extended element 75 effectively forms a rigid component of buoy without materially increasing the overall weight of the buoy while increasing the underwater mass of the buoy, the buoy tends to remain vertical, thus minimizing transmission block-outs caused by wind or wave knock-down." Of course it is to be understood that this stabilizing function could be used not only to stabilize a buoy but equally well to stabilize rafts or other like platforms.

The air release valve, previously mentioned, may be provided on all the configurations described, preferably being located at one or more of the high points of the inflated structure. Furthermore, it will be obvious to one skilled in the art that the pump means which is described as being .battery powered, may be replaced by a compressed gas supply and a water pump turbine.

The type of material used in the element maybe selected from any suitable substance which has good tensile properties in a thin-walled form and readily foldable and may conveniently be of slightly negative buoyancy. Such materials are, for example, polyethylene, Mylar (a trade mark of E. l. du Pont de Nemours & Co.), or a polyethylene mylar laminate, which is commercially available from Deerfield Laminates Ltd., of Toronto, Canada.

Under certain conditions, a structure according to the present invention may be towed behind a slow moving craft. Under such circumstances, a pump could be dispensed with and any suitable means, for example, a shaped neck or funnel-like header could be provided for supplying water to the towed element by ram effeet to inflate the element.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of the Unitd States is:

l. A vertically stabilized buoy, comprising: a hollow cylindrical canister having positive buoyancy; an antenna rigidly connected to the top of said canister, parallel with the axis thereof; an elongated, cylindrical, water inflatable, soft walled, water impermeable element rigidly connected at one end thereof coaxially to said canister and compactly folded therein;

trically coupled to said sensor through said tether for telemetering the output of said sensor by way of said antenna to a remote location; and

an impact removable closure member on said canister for retaining said element, pump, tether and sensor within said canister until impact with the surface of the water at which time said closure member opens and allows said element to be inflated in a vertical orientation to provide vertical stabilization for said antenna. 

1. A vertically stabilized buoy, comprising: a hollow cylindrical canister having positive buoyancy; an antenna rigidly connected to the top of said canister, parallel with the axis thereof; an elongated, cylindrical, water inflatable, soft walled, water impermeable element rigidly connected at one end thereof coaxially to said canister and compactly folded therein; means defining a fluid inlet in the other end of said element; a water pump coupled to said inlet defining means for directing ambient water into the interior of said element to cause said element to assume a semi-rigid structure of elongated cylindrical configuration; a condition sensor; tether means connected at one end to said pump and at the other end to said sensor for suspending said sensor from said pump; a transmitter mounted within said canister and connected to said antenna, said transmitter being electrically coupled to said sensor through said tether for telemetering the output of said sensor by way of said antenna to a remote location; and an impact removable closure member on said canister for retaining said element, pump, tether and sensor within said canister until impact with the surface of the water at which time said closure member opens and allows said element to be inflated in a vertical orientation to provide vertical stabilization for said antenna. 